Any good supply will work. Switching supplies are more prone to creating RF noise, but a well-built unit can be quite clean. Make sure all connections are good and proper voltage is making it to the rear of your Flex. What problem are you having? 13.8 VDC at 20A should be okay, but check the manual to be sure.

Thanks George for you advise....I'm using a Pyramid linear power supplies Output 13.8 VDC 40 Ampbut today...I was working digit modes (JT65), and noted on DDUtil screen voltage going down and change color of numbers from green....then yellow...and if I use more power got red... I checked analogical meters on power supplies with no change....I don't know if I'm a little ignorant in this matter..or beers have been too much today...

All well designed power supplies will work but when dealing with switching power supplies, some are quieter (RF noise) than others. Switching power supplies typically will produce more RF noise than linear power supplies. I only use Astron linear power supplies in my shack, and use a dedicated Astron RS-35M for my Flex 6700.

I agree with the above. The switchers are really convenient, but can be noisy. I use an Alnico DM33MV, which is a switcher, but it has been clean and very reliable. I found that my Flex 6500 was rebooting when I went to transmit, so I boosted the power supply to 14V output, and haven't had the problem since. So you should get a GOOD SOLID 13.8V out, and cranking it up a bit won't hurt anything. This PS has knobs for adjustment. It also has a knob that you can use to VARY THE FREQUENCY in case you get a spur. That will let you slide the spur up or down in frequency.

I use a 30 Amp Jetstream Switching power supply, no problems so far. I have noticed a lot of people that use longer than needed DC power cords and sometimes to small wire on their power cord. I like to use number 6 wire and at the Anderson power connectors I have to cut some of the wire away so it will fit in the connector. The thinner wire will work and be safe but you will have a voltage drop and the longer the cord the more the voltage drop. This is not the fault of the power supply its just what happens when you use a lot of current at a lot voltage.

I prefer the linear supplies to be sure no rf noise is generated in the supply. Astron is one of the best. I run a RS70 on mine, but the 35 should be fine as long as you don't have several other pieces of equipment on it.

1. Definitely avoid switching supplies..they all by design generate RF Noise.. some of the better brands have a knob to allow you to change the RF noise frequency but why bother... A good linear supply is much better without the noise issues

2. Do not undersize your power supply.... Most ham supplies are rated at peak rather than Average Power.. So a 35A Peak Supply likely will only handle 25A Average. A 100W Ham XCVR needs at least 20-25A Average and as much as 25-40A Peak.. so a reasonable supply would be a Astron 50A peak Linear Supply.

3. Do not use small cables- At currents of 40 A can produce quite a voltage drop over even a relatively short cable... #10 wire will work to 1Meter, #8 to 2 Meters, #6 for longer than 2 Meters..But you should also keep your cables as short as possible to reduce voltage drops..

Be careful with any cascaded Powerpoles, including Powerpole cubes; they can easily add up to a significant voltage drop at 20A-DC. This can undermine the benefit of using heavy gauge wire. I would first measure DC voltage with a DMM at the Flex's Powerpole connection. Record readings at several power levels all the way to 100W.

Provided the Pyramid 40A supply is regulating as designed, it should be more than adequate to power the Flex. I use a short run of #10 wiring from the supply's 1/4-inch terminal bolts to just one set of Powerpoles that connect to the Flex -- no other Powerpoles in the mix.

I had a very unsatisfactory result when using a PowerGate device and RigRunner DC power manifold. When using that arrangement as suggested by the manufacturer, a total of five (5) Powerpoles are used in the DC power path. In addition to loss, powering a transceiver through these devices can lead to a safety concern: If the path on the rig's negative lead opens for any reason, 20A of transceiver return current will find its way back to the power source through your accessory wiring as a negative lead substitute. These leads are not fused. This can cause negative leads on +12V accessories to burn and start a fire. At the very least, Powerpoles should be locked in tandem with roll pins (or similar locking mechanisms) to mitigate the effect of a missing negative return to a transceiver. The positive conductor should disconnect with the negative.

I now limit use of the RigRunner to only +12V, low-current accessory devices. Transceivers connect directly to a 30A power supply with no other connections or devices in between. This way, it's almost impossible for the negative lead to accidentally open between the Flex and supply.

I'd like to share my experience and thanks to all you "Hams" and friends for help you gave me

This is what I read...and what I did

1st thing: "Definitely avoid switching supplies" ...my power supplies is linear, so I decided to check it exhaustively: 13.98 VDC 40 Amp after test ..so It is GOOD....so I took Howard (KY6LA) advise avoiding Switching Supplies

2nd thing: "I had a very unsatisfactory result when using a PowerGate device and RigRunner DC power manifold."Paul (W9AC) it was really a great advise, his experience with RigRunner made me think and check my RigRunner 4008H which was bought to keep "order" in my shack....however test showed me 0.4 voltage drop, 0.9 v after turning on Antenna Tuner ......so I took Paul advise using it only for low-current accessory device

3rd thing: "Do not use small cables" Howard(KY6LA).................... I took this advise seriously cause I didn't know what cable number came with my flex....after checked it I guess could be a #12 or #10 . I Decided to keep it cause It's the stock one, I'm sure Flex people wouldn't let themselves to have that kind of mistake...It must be right one.......

4nd thing: "No one has mentioned the cable between Flex and PS. An additional 15A can result in a several volt drop in wiring, connectors, and especially fuses"Stan (VA7NF) and "This is not the fault of the power supply its just what happens when you use a lot of current at a lot voltage"Delbert and " keep your cables as short as possible to reduce voltage drops"Howard (KY6LA)................I decided go directly from power supply 13.8VCD 40Amp to Flex with less than 2 meters #12 cable.......

Glad you got your power Supply issues figured out.. But looking at your display, you are over driving your level.. You can keep from distorting your input audio , raise the power out, and lower the TX DAX level to bring down you audio level below "0" dbm.. I run my power at 100% and adjust the TX DAX level to give the RF output I need..

Astron RS-35M for my Flex 6300. I had a switching power supply that QST said was very quiet. One day I did a test, hooked up a 12V battery to the radio. Opened the panadapter really wide to see all the stuff on the band. Turned the power supply on and off, on and off. There were LOTS of birdies in nearly all the ham bands! Sold it and got the Astron RS-35M the next day. All you guys that say switching power supplies are OK, I challenge you to do the same test.73, Dave

Burt, Corsair computer power supplies are much better quality design and filtering than most stock computer power supplies. I always had to change the computer power supply out, especially on off the shelf computer purchases, to eliminate pick up of trash (noise hash and birdies) on the Low Bands where I predominately operate. Replacement of the computer power supply to the Corsair supply eliminated any trace of noise generated by the former power supply.

I'm pretty sure I have seen you present this question before and got the same answers each time.. Now either we are insane... or...

I too replaced all 9 computer supplies in my Shack with Corsairs. As Well I did that to the other computers in the house too. Definitely improved it. But I also grounded cases, removed paint from screw holes to improve Faraday cage effect

I might add that Thermaltake and cooler master supplies are very quiet also. All I have are the 500 watt or larger. Three cooler master and one Thermaltake all very quiet. A lot of monitors produce noise also. I wound up using a 24 inch Vizio E razor 1080p set that eliminated all of my birdies on 20m through 6m.

My power supply is an Astron 35A but after I purchased the Flex 6300 I also added a smalldigital volt meter I picked up on eBay to monitor the voltage output like a 35M analog meter.Hooked it to the output of the PS. This astron is almost 20 years old, many years ago Imounted two small quiet muffin fans directly to the heat sink also powered from the output.The PS runs VERY cool, I believe the pass transistors have lasted this long because of the fans.

I have an Astron 30S switcher on the shelf for a backup but fortunately have never needed it.

One other thing about the switcher supply I used when I built my Flex desktop computer.At first I bought cheap from a local computer shop, BIG mistake, BIG Birdies EVERYWHERE!Picked up a well filtered Corsair switcher supply, problem solved...